Commercial pest elimination services have used devices to dispense pesticides or insecticides for a long time. These devices include a source of the pesticide, a source of air pressure and a wand or other dispensing means to place the pesticide in the desired location, often mounted on a cart for mobility, see U.S. Pat. No. 3,265,308.
U.S. Pat. No. 3,194,438 discloses a cleaning machine designed to dispense chemicals from tanks 7 mixed with water and air. The tanks are controlled by valves 30 and mixed with the air in nozzle N.
U.S. Pat. No. 3,575,348 describes a device for rinsing and washing using water pressure to dispense an active material from tank 32. The water and chemical are mixed in venturi device 42.
U.S. Pat. No. 3,797,744 discloses a cleaning device comprising a series of tanks for cleaning chemicals, a source of air pressure and water. The chemicals are mixed with the air and water in the spray nozzle. The device also shows a separate nozzle for dispensing a mixture of air and oil.
It is also known to use an electrostatic charge to assist in the dispensing of insecticides, see U.S. Pat. Nos. 4,341,347, 4,275,846, 4,356,528, 4,358,059, and 4,362,275.